Tickler assembly for riser pipe of fused salt electrolysis cell for the production of sodium



Aug. 11, 1970. c. T. GALLINGER 3,523,885 TICKLER ASSEMBLY FOR RISER PIPE OF FUSED SALT ELECTROLYSIS v CELL FOR THE PRODUCTION OF SODIUM Filed May 10, 1967 2 Sheets-Sheet 1 INVENTOR CLYDE T. GALLINGER D3 BY AGENT Aug. 11, 1970 c, GALLINGER 3,523,885

TICKLER ASSEMBLY FOR RISER PIPE OF FUSED SALT ELECTROLYSIS CELL FOR THE PRODUCTION OF SODIUM Filed May 10, 1967 2 Sheets-Sheet 2 T0 TICKLER CLAMP -|n T0 RACK --:I 121 I IM TO AIR SUPPLY I03 T0 RECEIVER AGITATOR INVENT OR United States Patent US. Cl. 204-245 6 Claims ABSTRACT OF THE DISCLOSURE A tickler assembly for the riser pipe of a fused salt electrolysis cell for the production of sodium, which assembly comprises (A) a tickler designed to free solid deposits, e.g., calcium deposits, from the inner walls of the riser pipe, in combination with (B) a first driving means, preferably a double-acting gas cylinder, for imparting vertical movement to the tickler and (C) a rack and pinion gear in combination with a ratchet and a second driving means, preferably a double-acting gas cylinder, for imparting intermittent rotary motion to the tickler, together with (D) means, preferably a reversing gas valve, for intermittently reversing the directions of the drives of said first and second driving means. The tickler assembly also includes means for bringing the vertical movement of the tickler to a sudden jarring stop to cause dislodgmement of solids from the tickler. Preferably, the tickler assembly for the riser pipe is operated in conjunction with an agitator assembly for a sodium receiver into which sodium passes from the top of the riser pipe into the receiver by way of a Weir connecting the two. The agitator assembly for the receiver comprises a rotary agitator including scraper blades for cleaning the side walls of the receiver and the weir between the riser pipe and receiver, and a reversible drive means, preferably a double-acting gas cylinder, in association with a ratchet, for intermittently rotating the agitator.

BACKGROUND OF THE INVENTION Sodium is produced commercially by the electrolysis of a fused electrolyte comprising sodium chloride in an electrolysis cell of the Downs type, described in Downs US. Pat. 1,501,756. Such cells employ bottom-mounted vertical cylindrical anodes which are surrounded by cylindrical cathodes so that each cathode and anode combination defines an annular electrolysis Zone into which is positioned a foraminous diaphragm serving to separate the electrolysis products from each other. The chlorine product rises from the anode through the electrolyte into a hood from which it is withdrawn from the cell. The sodium product rises from the cathode through the electrolyte into a collector, generally an inverted annular trough, from which the sodium rises further into a vertical riser pipe which conveys the sodium out of the upper part of the cell and into a receiver.

Because of the high melting point of sodium chloride, it is customary to employ as the electrolyte a mixture of sodium chloride and one or more other metal chlorides such as calcium chloride, the function of the latter being to lower the melting point of the electrolyte thus permitting operation of the cell at a lower temperature. The use of such a mixture of chlorides as the electrolyte results in a sodium cathode product which contains anothermetal, e.g., calcium, as impurity. As the sodium rises from the cell through the riser pipe, the upper portion of which is generally provided With cooling fins, most of the second metal, such as calcium, will precipitate as a solid from the sodium and, because of its greater 3,523,885 Patented Aug. 11, 1970 density, will sink in the riser pipeand return to the body of electrolyte. Calcium returned to the electrolyte in this manner will react with the sodium chloride present to produce metallic sodium and calcium chloride. Thus, the function of the riser pipe is that of purifying the sodium product so that the sodium which passes from the top of the riser pipe into the receiver will contain only small amounts of metal impurities such as calcium. The impurities which are precipitated in the riser pipe tend to deposit as a solid on the inner walls of the pipe. If such solid deposits are not removed, they eventually would completely plug the riser pipe. It is, therefore, essential that such deposits be removed at least periodically from the riser pipe walls. This is customarily done by the use of devices, commonly referred to as ticklers, which are generally operated on a periodic basis. Various types of mechanically driven ticklers have been proposed, for example, in US. Pat. 2,770,364, 2,770,592, 2,861,938 and 3,037,927.

The above patents describe tickler assemblies which combine various types of ticklers with certain mechanisms for mechanically driving the ticklers. The tickler usually consists of a shaft which is generally coextensive in length with the length of the riser pipe except for a portion of the shaft which extends through the top of the riser pipe for connection with the driving mechanism. The shaft in the riser pipe is usually provided with cleaner blades or scrapers designed to remove solids from the inner walls of the riser pipe as the shaft is driven vertically and/or rotated by the driving mechanism. The type of cleaner blades or scraper elements of the ticklers which have been proposed include a plurality of cutting hoops designed to scrape the riser pipe wall when the tickler is moved vertically, blades in the form of paddles positioned in spaced relationship along the vertical length of the tickler shaft, scraper blades of arcuate shape with a forward cutting edge, and vertically disposed scraper blades having cutting edges. All such scraping or cleaning elements are intended generally to exert a scraping action over the entire inner surface of the riser pipe during the operation of the tickler.

While the tickler assemblies described in the above patents are useful, their scraping action is not as effective as desired, particularly for breaking up and removing solid encrustations from the riser pipe walls. Furthermore, they are not designed to handle simultaneously the removal of solids from the walls of the sodium re ceiver and from the weir or opening between the receiver and the riser pipe, and they require rather frequent repair or changing and considerable manual attention during operation.

The present invention relates to an improved mechanical tickler assembly with a sodium receiver agitator assembly, in which assemblies are employed improved driving mechanisms assuring a long effective life with little, if any, manual attention being required.

As indicated above, the sodium product rising in the riser pipe of a Downs type cell flows from the riser pipe into a product receiver, generally by way of an opening or weir connecting the riser pipe with the product receiver. The sodium delivered into the receiver generally has a relatively loW calcium content. Nevertheless, precipitation of calcium on the walls of the receiver does occur and calcium deposits tend to block passage of the sodium through the weir. The combination of the tickler assembly of the present invention with the receiver agitator assembly of the invention is designed not only to remove solid deposits such as calcium from the inner walls of the riser pipe, but also to accomplish the removal of such deposits from the walls of the re ceiver and also from the weir connecting the riser pipe and the receiver.

ice

3 SUMMARY OF THE INVENTION The riser pipe tickler assembly of the invention comprises (A) a tickler for insertion into the top of the sodium riser pipe and operable therein to free solid deposits from the inner walls of the riser pipe, in combination with (B) a first driving means for imparting intermittent reciprocal vertical movement to the tickler, (C) a rack and pinion gear in combination with a ratchet and a second driving means for intermittently imparting a partial rotation of the tickler in one direction, and (D) means for intermittently reversing the directions of the drives of said first and second driving means. The tickler assembly also includes means for bringing the vertical movement of the tickler to a sudden jarring sto 121 a preferred embodiment of the invention, the above tickler assembled is operatively combined with an agitator assembly for a sodium receiver connected to the riser pipe by way of an opening or weir through which sodium flows from the riser pipe into the receiver, which agitator assembly comprises an agitator which is rotatable within the receiver and includes blades for cleaning the receiver side walls, in combination with means for intermittently rotating the agitator in one direction, which means comprises a driving means in combination with a ratchet, and means for intermittently reversing the direction of the drive of the driving means.

DESCRIPTION OF THE DRAWINGS FIG. 1 is a plan view of a preferred embodiment of the riser pipe tickler assembly of the invention showing also a receiver provided with an agitator assembly in accordance with the invention.

FIG. 2 is a front elevation view, shown partly in section, of the riser pipe tickler assembly and receiver agitator assembly of FIG. 1.

FIG. 3 shows diagrammatically the pneumatic system employed for operating the assemblies of FIG. 1.

FIG. 4 is a motion diagram depicting the vertical and rotational movements of the tickler of FIG. 1 under normal operating conditions.

FIG. 5 is a motion diagram depicting the rotational movements of the tickler of FIG. 1 under normal operating conditions.

FIG. 6 is a motion diagram depicting the vertical and rotational movement of the tickler of FIG. 1 when the tickler encounters obstinate solid obstructions during its operation.

Before describing in detail the structures represented by FIGS. 1, 2 and 3, it should be pointed out that the riser pipe of a sodium cell of the Downs type rises from within the cell and extends vertically for a considerable distance above the cell where it discharges into a sodium receiver. Generally, the upper part of the riser pipe, which is external of the cell, is provided with cooling fins in order to facilitate cooling of the rising column of sodium so as to effect precipitation of metal impurities therefrom. On the other hand, the portion of the riser pipe which is internal of the cell is usually somewhat smaller in diameter than the external part of the riser pipe, which bottom part opens into the sodium col lector positioned above the cell cathode. The general arrangement of the riser pipe with respect to the sodium cell is well understood and is shown in the drawings of most of the patents referred to above. Accordingly, the attached drawings do not show the association of the riser pipe with the sodium cell, it being understood that the association is the usual one indicated in the patents referred to above.

FIGS. 1 and 2 show a riser pipe 108 whose upper part is provided with cooling fins and whose lower part is of smaller diameter than the upper part, which upper and lower parts are connected by a restricted portion 115. Extending through the riser pipe is a tickler shaft 113 which is generally coextensive in length with the length of the riser pipe except that its upper end extends through cover plate 109 and terminates at tickler clamp 116. Shaft 113 is provided with tickler blades 114 arranged in pairs mounted on the shaft at regular intervals through out the shaft length. The tickler blades of each pair are mounted on shaft 113 at substantially right angles thereto. They are generally rectangular in shape, the length of each blade being such that the spacing between its outer end and the wall of the riser pipe is but a fraction of an inch, e.g., about A inch. Each blade of a pair is mounted on the shaft 180 from the other blade of that pair. Preferably, all pairs of blades are mounted in the same vertical plane. In general, the length of each blade is 4 to 7 times its width and their construction of steel bars or plate about A to inch thick insures sutficient ruggedness for the operation intended.

Intermittent vertical reciprocal movement of the tickler is imparted by the action of a double-acting gas cylinder 102, while intermittent partial rotation of the tickler in a single direction is imparted by the action of doubleacting gas cylinder 101 in conjunction with rack 105 and pinion gear and ratchet 118. Intermittent reversal of the directions of drive of gas cylinders 101 and 102 is effected by reversing gas valve 104.

Shown associated with riser pipe 108 is sodium receiver 110 the upper part of which is connected to the riser pipe through weir 120. Receiver 110 is provided with an agitator 111 which includes blade 112 which extends into weir during its rotation with just sufiicient clearance between blade 112 and tickler blade 114 so as to permit both blades to rotate simultaneously. The purpose of receiver agitator 111 is to keep suspended the calcium deposits that are formed in the sodium in the receiver so that they will be removed along wih the sodium as the latter flows out of the bottom (not shown) of receiver 110. Rotation of receiver agitator blade 112 together with the rotation of the top riser pipe agitator blade 114 cooperates to clear calcium deposits from weir 120, thereby permitting free flow of sodium from the riser piper into the receiver. Receiver agitator 111 also functions to scrape off solid deposits that may tend to accumulate on the inner walls of receiver 110. Agitator 111 is intermittently rotated in a single direction by means of double-acting gas cylinder 103 operating in conjunction with ratchet 119 and reversing gas valve 104. Activation of gas cylinder 102 drives tickler shaft 113 intermittently up and down, while activation of double-acting gas cylinder 101 is conjunction with rack 105 and pinion gear and ratchet 118 and reversing gas valve 104 causes tickler shaft 113 to rotate partially after each up and down movement thereof.

As shown in FIG. 3, double-acting gas cylinders 101, 102 and 103 are connected by gas lines 117 so as to be controlled by reversing gas valve 104 which is connected to a gas supply by valve 121. Thus, air under pressure admitted to the system through valve 121 passes by way of reversing gas valve 104 and gas lines 117 to gas cylinders 101, 102 and 103 which activate rack 105 and pinion gear and ratchet 118, tickler shaft 113 and receiver agitator 111, respectively. Gas cylinder 101 activates rack 105 and pinion gear and ratchet 118 causing tickler shaft 113 to rotate the desired extent, e.g., about 80, which rotation is always in the same direction. As the rotation occurs, the travel of rack 105 causes plunger 107 to strike reversing switch 106 of gas valve 104 which then activates the reversal of gas cylinders 101, 102 and 103. Activation of gas cylinder 103 together with ratchet 119 effects rotation of receiver agitator 111, which rotation is, e.g., about 80.

Because of the actions of ratchets 118 and 119, the rotations of the tickler in the riser pipe and of the agitator in the sodium receiver will always bein a single direction. Thus, when switch 106 reverses the action of gas cylinders 101 and 103, the rotations of both the riser pipe tickler and the receiver agitator will cease due to the action of ratchets 118 and 119, but at the next reversal of switch 106 the riser pipe tickler and the receiver agitator will again be rotated as previously. Thus, the rotations of the tickler and the agitator will be intermittent and, as indicated previously, will always be in a single direction. As switch 106 is reversed back and forth, gas cylinder 102 causes the tickler comprising shaft 113 and blades 114 to be alternately raised and lowered in riser pipe 108. The length of the vertical travel of the tickler is adjusted so that at the end of the down stroke tickler clamp 116 will strike riser pipe cover plate 109 and thereby impart a jarring stop to the tickler, the effect of which is to jar loose solids that may have accumulated on tickler blades 114.

FIGS. 4, 5 and 6 depict the motion patterns for the riser pipe tickler during normal operation and also in those few instances when an obstruction on the inner walls of the riser pipe may 'be so obstinately held as to cause operation of the tickler in an abnormal way or, in extreme cases, the cause the tickler to become stuck, in which case resetting of the drive mechanism will be necessary.

FIG. 4, depicting the motion pattern during normal operation of the riser pipe tickler, indicates that the vertical motion of the tickler will be alternately upward then downward and that after each upward and downward movement or stroke, a partial rotation of the tickler will occur. Thus, with the tickler beginning in the uppermost position 1, the vertical movement would be down to the bottom of the stroke at position 2, following which the tickler would rotate to position 3 and then be raised to position 4, back down to position 5, rotated to position 6, etc. As indicated, the rotational movements in going from positions 2 to 3, 5 to 6 and 8 to 9 occur at the bottoms of the up-anddown strokes. The rotations occurring at the bottom of each down stroke occur only in one direction because of the action of pinion gear and ratchet 118 in combination with the rack 105. Each rotation is going from position 2 to 3, or 5 to 6, etc., will be a rotation only of, for example, 80, the extent of the rotation being governed by the length of travel set on rack 105. During such rotations, the tickler will be in its bottom position whereby the constricted position 115 of the riser pipe will be wiped free of loose solid material which may have settled thereon from the upper portion of the riser pipe, and various other portions of the riser pipe opposite the various riser pipe blades will be similarly wiped. This includes the uppermost tickler blade which, at the bottom part of the down stroke, will be opposite blade 112 of receiver agitator 111. With these two blades, i.e., upper blade 114 of the riser pipe tickler and blade 1-11 of the receiver agitator, in close operative alignment with each other and simultaneously rotated, they will effectively cooperate with each other to remove any solid accumulation in weir 120. The spacing of tickler blades 114 vertically on the shaft 113 should be such that all inner surfaces of the riser pipe will be acted upon by the tickler blades during the up and down movements of the tickler.

As indicated, the degree of rotation of the tickler at the end of each up and down stroke will be governed by the effective length of rack 105, which length will generally be such that the rotation of the tickler will be about 35 to 135, preferably 70 to 100, each time the tickler is rotated. By adjusting the travel length of rack 105 so that the angle of rotation of each cycle, when divided into 360 will give an odd number, the starting point for each rotation will be different each time the tickler is rotated. This is indicated by FIG. 5 in which the circle represents a complete rotation of 360. As indicated, between the 1 and 2 vertical strokes and the 3, 4 and 5 vertical strokes there will be a rotation of the tickler from position A to position B, and between vertical strokes 3, 4 and 5 and vertical strokes 6, 7 and 8 there will be a rotation from point B to point C, etc.

Thus, following each down stroke of the tickler, a partial rotation will occur before the next up stroke and the position of the tickler blades in the circle will be different at the end of each period of rotation from the position at the end of the preceding period of rotation. Consequently, the circular position of the tickler blades will be different at the beginning of each up and down movement from the position at the beginning of each preceding up and down movement, the result being that all portions of the inner walls of the riser pipe will progressively be subjected to the knifing or chopping action of the edges of the tickler blades against any solid deposits that may be present on the inner walls of the riser pipe. Such knifing or chopping action has been found to be highly effective in removing solid deposits and much more eifective than a simple wiping action by the sides of rotating blades.

Normally operation of the tickler once each hour for a duration of 15 seconds to 3 minutes will suffice to keep the inner walls of the riser pipe effectively clean of undesirable solid deposits. However, the frequency of the periods of operation and the duration of each period may be varied considerably and will be set as required for any given cell. Should a solid obstruction highly resistant to dislodgement be encountered by a tickler blade during the down stroke at point 2, indicated by a small triangle in FIG. 6, the gas feeds to gas cylinders 101 and 102 would become equalized so that the movement of the tickler would then occur along line 2-3 instead of along the dotted line 2-2a. The slope of line 2-3, or the magnitude of angle 4:, will be determined by the resistance of the obstruction. With such an oblique travel of the tickler blade along line 2-3, the blade will slice across the obstruction and generally move it. When the tickler then reaches point 3, it will proceed as normal through its up and down and intermediate rotary movements until the tickler again strikes the obstruction at point 2 if it has not already been removed. Thus, the obstruction at point 2 would be subjected repeatedly to the action of the tickler and almost always will be eventually removed. Obstructions indicated by small triangles, if encountered at point 7 or point 13 during vertical movements would be similarly acted upon by the tickler. Should an obstinate obstruction be encountered during the rotation of the tickler, as indicated by the small triangle at point 15, the tickler would become stuck in the sense that a resetting of the reversing valve 104- would be necessary. It should be pointed out, however, that such sticking of the tickler so as to require resetting is a seldom occurrence when the tickler assembly is operated at judiciously spaced intervals, thereby avoiding any massive accumulation of solid deposits in the riser pipe during the operation of the sodium cell. When the periods of operation of the tickler assembly are judiciously timed and spaced, the normal movement pattern of the tickler will be that indicated by FIGS. 4 and 5.

The magnitude of the up and down movement of the tickler will, of course, be limited and generally will not exceed about 6 inches. The preferred vertical movement will generally be about 2 to 4 inches, and the vertical spacing of the tickler blades upon the tickler shaft will be such that when the tickler is in its bottom-most position, the upper tickler blade will be opposite weir 120. This is the position the tickler will be in when each partial rotation will occur. Due to the synchronization of the rotation of receiver agitator 111 with that of the tickler, the uppermost tickler blade will cooperate with agitator blade 112 to keep weir free of excessive solid deposits. The synchronization of the rotary movements of the tickler and the receiver agitator 111 is due to the fact that both air cylinder 101, which powers the rotary movement of the tickler, and air cylinder 103, which powers the rotation of receiver agitator 111, are activated by the same gas valve, i.e., gas valve 104.

7 DESCRIPTION OF THE PREFERRED EMBODIMENTS The preferred tickler assembly for the riser pipe will be that described above and represented by FIGS. 1, 2 and 3. As indicated in the above description, the preferred means for intermittently driving the tickler vertically and for intermittently imparting partial rotation thereto at the bottom of the down stroke will be, respectively, double-acting gas cylinders 102 and 101. Similarly, the means for intermittently rotating receiver agitator 111 will be a double-acting gas cylinder 103, all of which gas cylinders will be activated by gas supplied through a reversing gas valve 104. Regular periodic operations of the tickler assembly and the receiver agitator assembly can be readily made to occur automatically by programming the operations with a timer.

When the preferred tickler and receiver agitator assemblies represented by FIGS. 1, 2 and 3 were used in a bank of sodium cells during operations over diaphragm lives of 150 days and averaging days, i.e., the period at the end of which a new diaphragm is required, it was found that no tickler changes were required during the entire period of the diaphragm life of any of the cells. When a new diaphragm is required, the top part of the cell must be removed for the insertion of a new diaphragm and any repair or replacement of parts of the upper part of the cell that is required is made at that time. Therefore, when the life of a tickler assembly is at least as long as the diaphragm life, the latter rather than the tickler life becomes controlling. With the present tickler assembly, it has been found that the diaphragm life rather than the tickler life becomes the controlling factor.

While FIGS. 1 and 2 show a tickler provided with paddle type blades spaced vertically along the tickler shaft, such blades may be replaced by other suitable scraping or cleaning devices. Thus, instead of employing paddle type blades as shown in FIG. 2, the cleaning or scraping device may consist of similar blades with adjacent pairs thereof connected together in alternate manner by a single vertical strip at their outer ends so that upon rotation of the tickler all surfaces of the inner walls of the riser pipe will be simultaneously scraped or wiped. Also, tickler scraping elements in the form of helical blades, scraping hoops or a plurality of vertically disposed blades uniformly spaced about the tickler shaft can be used, although tickler blades of the paddle type indicated in FIG. 2 are generally preferred because of their simplicity and ease of forming and their generally high effectiveness.

Instead of driving the gas cylinders of FIGS. 1 and 2 with air under pressure, other suitable gases such as nitrogen may be employed. Furthermore, instead of double-acting gas cylinders as the driving means, reversible motors and suitable switching mechanisms, air or gas motors or hydraulic cylinders may be employed. Also, in place of reversing gas valve 104 of the drawings, other suitable switching means such as solenoid valves with appropriate switching mechanisms can be used. However, the pneumatic driving and valving mechanisms described above are distinctly preferred for cost reasons and for their generally efficient operation in conjunction with the tickler and receiver agitator described.

CI claim:

1. A mechanical tickler assembly in combination with a vertical riser pipe of a fused salt electrolysis cell for the production of sodium, said assembly comprising (A) a tickler inserted into the top of said riser pipe and operable therein to free solid deposits from the inner walls of said riser pipe, in combination with (B) a first driving means for imparting intermittent reciprocal vertical movement to said tickler within said riser pipe (C) a rack and pinion gear in combination with a ratchet and a second driving means for intermittently imparting solely a partial rotation of said tickler in said riser pipe an odd number of degrees of from 35 to in one direction, (D) means for reversing the directions of the drives of said first and second driving means, and (E) means for bringing the vertical movement of said tickler to a jarring stop.

2. A tickler assembly according to claim 1 wherein said first and second driving means are double-acting gas cylinders and the means for reversing the directions of their drives is a reversing gas valve.

3. A tickler assembly in accordance with claim 2 wherein the tickler comprises a drive shaft extending substantially the entire length of the riser pipe and a plurality of pairs of cleaner blades projecting at substantially right angles from said shaft and spaced substantially evenly along its length in the same vertical plane.

4. A tickler assembly in accordance with claim 1 in combination with an agitator assembly in a sodium receiver connected to the upper part of the riser part by a weir through which sodium product flows from said riser pipe into said receiver, said agitator assembly comprising (A) an agitator which is rotatable within said receiver and includes blades for cleaning the side walls of said receiver, (B) means for intermittently rotating said agitator in one direction, said means comprising a driving means in combination with a ratchet and (C) means for reversing the direction of the drive of said driving means.

5. A tickler assembly in combination with a receiver agitator assembly in accordance with claim 4 wherein the tickler in the riser pipe includes a pair of paddle blades operable to rotate opposite the weir connecting the riser pipe and the sodium receiver, and wherein the agitator of the receiver agitator assembly includes a blade operable to rotate through said weir, whereby upon rotation of said tickler and said receiver agitator solids accumulated in said weir are removed therefrom.

6. A tickler assembly in combination with a receiver agitator assembly in accordance with claim 5, wherein the first and second driving means in the tickler assembly and the driving means in the receiver agitator assembly are each a double-acting gas cylinder, all of which driving means are operatively controlled by a common means for effecting reversals of the directions of the drive of each of said driving means, which common means for effecting said reversals is a reversing gas valve.

References Cited UNITED STATES PATENTS 2,068,681 1/1937 Hulse et al. 204-68 2,130,801 9/1938 Hulse 204-68 2,770,364 11/1956 Honea 204-247 2,770,592 11/ 1956 Fentress 204-245 2,861,938 11/1958 Glascodine 204-243 2,944,955 7/1960 Fentress 204-245 3,037,927 6/1962 Gallinger 204-245 WINSTON A. DOUGLAS, Primary Examiner C. F. L FEVOUR, Assistant Examiner U.S. Cl. X.R. 136-68 

